package icu.lookyousmileface.readeandwritelock;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * @author starrysky
 * @title: ReadAndWriteLockUse
 * @projectName Juc_Pro
 * @description:  读写锁
 *  * 独占锁（写锁） 一次只能被一个线程占有
 *  * 共享锁（读锁） 多个线程可以同时占有
 *  * ReadWriteLock
 *  * 读-读  可以共存！
 *  * 读-写  不能共存！
 *  * 写-写  不能共存！
 * @date 2021/1/293:08 下午
 */
public class ReadAndWriteLockUse {
    public static void main(String[] args) {
        MyCache myCache = new MyCache();

        for (int i = 1; i <= 6; i++) {
            final int  temp = i;
            new Thread(()->{
                myCache.put(String.valueOf(temp),String.valueOf(temp));
            },String.valueOf(i)).start();
        }

        for (int i = 1; i <= 6; i++) {
            final int  temp = i;
            new Thread(()->{
                myCache.get(String.valueOf(temp));
            },String.valueOf(i)).start();
        }
    }
}

class MyCache{

    private final Map<String,String> map = new HashMap<>(16, 0.75F);
    private ReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();

    // 存，写入的时候，只希望同时只有一个线程写
    public void put(String key,String value){
        reentrantReadWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+":正在插入"+key);
            map.put(key, value);
            System.out.println(Thread.currentThread().getName()+":"+key+"插入完成!");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            reentrantReadWriteLock.writeLock().unlock();
        }
    }
    // 取，读，所有人都可以读！
    public void get(String key){
        reentrantReadWriteLock.readLock().lock();
        try{
            System.out.println(Thread.currentThread().getName()+":正在读取"+key);
            String value = map.get(key);
            System.out.println(Thread.currentThread().getName()+":"+key+"读取完成!"+"值:"+value);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            reentrantReadWriteLock.readLock().unlock();
        }
    }
}

